Field of the Invention
The present invention relates to an electroconductive material for a connection component, such as a terminal, mainly used in the field of automotive wiring harnesses and general consumer products, and particularly to an Sn-plated electroconductive material for a connector capable of realizing decreased fretting corrosion.
Description of the Related Art
A mating connector consisting of a male connector and a female connector is used for connecting electrical cables in an automobile (automotive wiring harness) or the like. A male terminal and a female terminal, generally stamped out from a tin plated copper alloy sheet or strip, are embedded in a male connector and a female connector, respectively.
In the field of automobile electric equipment, use of multi-terminalization of connectors has progressed due to the advancement and wide use of electronic control. The force required for inserting connectors has increased such that the physical load on workers has increased. Thus, it is desired to decrease the connector inserting force. It is effective to decrease the contacting pressure of the terminals to decrease the inserting force of a connector.
Lowering the contacting pressure in Sn-plated small terminals or the like, however, presents the problem of fretting corrosion. Fretting corrosion, the abrasion of Sn on the male and the female terminals, is caused by repeated sliding between the male and the female terminals due to vibration of an engine of the automobile and vibration while the automobile is moving. The abraded Sn powder is then oxidized. The oxidized Sn powders subsequently deposit around the contact point in large volume and invade the contact point, which increases contact resistance at the contact point.
JP-A-2006-183068, which corresponds to US 2008/0090096, the disclosure of which is incorporated herein by reference in its entirety, discloses an electroconductive material for a connection component obtained by plating Ni, Cu, and Sn in order on a roughened surface of a copper alloy base member followed by reflow treatment. The electroconductive material for a connection component includes a surface coating layer including a Ni coating layer, a Cu—Sn alloy layer, and a Sn coating layer formed on a surface of the copper alloy base member, wherein the Cu—Sn alloy hard coating layer is formed to be partially exposed at the outside surface of the Sn coating layer so as to decrease the connector inserting force without decreasing the contacting pressure of the terminals.